1. Field of the Invention
This invention concerns a device for use in electrophoresis.
2. Description of the Background Art
In an electrophoresis process a gel is subjected to a high electric tension on at least two sides. The applied tension results in migration of the molecules in the gel, a shorter or longer distance depending on, for example, the electric charge of the molecules. Hereby the movement direction of the molecules is always perpendicular to the equipotential lines, i.e. lines having the same potential in the gel. Totally decisive for a reliable result in respect of detection of separated molecules, is that the equipotential lines are straight and parallel, since otherwise erroneous detection occurs. Possible leaks from the gel enclosure thus result in electric contact between the gel and a liquid bath put under tension, resulting in sideward current leaks, curved equipotential lines and "curved migration" of molecules.
While forming the gel in the gel enclosure, it is further essential to obtain as homogeneous and even thick a gel as possible since also variations in the gel thickness result in undesired deviations from accurate equipotential line paths.
Known devices of the previously mentioned kind unfortunately suffer from the above discussed problems at a smaller or greater extent. As examples of devices which to date are used for clamping gel slab assemblies, those may be mentioned which clamp together the gel unit using screw fasteners, whereby a number of screw means which are distributed over the side edge are arranged to exert the desired pressing force. These previously known devices, however, have not satisfactory solved the problems in question, since an inherent adjustment variation exists because of the individually tightened screw means. This is also the case if the screws, as in certain cases, have been tightened with a torque indicator.
Another known device is applied by two jaw portions being pressed over the edge of the gel assembly by means of an eccentric mechanism. Also this device, however, suffers from problems related to exerting even pressure. A further problem is that of sideward movement, which may occur in connection with the tightening of the eccentric, and which may result in an undesired mutual sideward movement between the glass plates which are parts of the assembly. A further problem is insufficient clamping force, which results in the above discussed sideward leakage, particularly when forming the gel.
U.S. Pat. No. 4,035,377 concerns a slab gel electrophoresis apparatus having clamps of the paper clamp type for holding the plates together. The lengths of the clamping portions are such that an untrained person by mistake can apply the clamping force inside the spacing strips. The clamps are applied by a lateral movement over the plates, leading to possibility of inexact positioning and force distribution. The large dimensions of the clamps makes it necessary to remove some of them when carrying out the electrophoresis process.